High intensity discharge lamps are typically used in applications where the lamp is spaced a substantial distance from the surface to be lighted, such as, a sports arena, a traffic highway interchange, a warehouse, shopping malls, atriums, or other similar applications. When the discharge lamp burns out through usage, it can be expensive and bothersome to replace the lamp. It is particularly desirable to reduce the number of times that it is necessary to re-lamp a particular fixture and avoid resulting interruptions. It is also desirable to provide a construction wherein the life of an operating fixture is extended to reduce the frequency of re-lamping the fixture.
High intensity discharge lamps are energized by an electric current to create a metallic vapor and the current through the lamp causes high intensity illumination. Lamps of this type do not illuminate instantaneously, but require time for the lamp to ignite. When a high intensity discharge lamp is fully operational and the current to the lamp is interrupted for a short period of time, the lamp will not reignite immediately. The lamp must cool down before it will reignite. The period of cooling varies from lamp to lamp. The cooling may be as short as a few minutes, or as long as twenty minutes. In certain instances the period of non-ignition of high intensity discharge lamps may be dangerous, such as, in a sports arena. A crowd of spectators could panic because of the darkness of the arena. Various systems are used to solve the problem, such as, providing an emergency lighting system in a sports arena, those systems typically providing enough light to allow sports fans to leave the arena.
It is desirable to provide a high intensity discharge lighting system in which the time between re-lamping is extended, as well as provision for instant or reduced restrike time for lamps that experience a momentary power interruption. Interruption of electric current to a first high intensity discharge lamp and re-establishment of the current ignites another high intensity discharge lamp to provide lighting in the same area as where the first lamp provided lighting.